Kazuya Takamori is Suzume Imamura's boyfriend. He originates from a wealthy family where both parents were frequently absent due to work, returning home only a few times yearly and interacting minimally with him even then. This prolonged parental neglect and emotional isolation fostered intense childhood loneliness. As he grew older, these unresolved feelings manifested as delinquent behavior, including violence and bullying peers, driven by a search for companionship and validation. His emotional state deteriorated until he felt unwanted by his parents and the world, culminating in a suicide attempt where he tried to drown himself in a canal.

Suzume Imamura intervened during this attempt, physically stopping him and offering the vital emotional connection he craved. This encounter proved pivotal, prompting Kazuya to reevaluate his life and develop a profound appreciation for his existence. His relationship with Suzume became central to his identity, marked by deep care and devotion. He particularly values her perpetually cheerful and optimistic personality, traits others sometimes found childish or annoying. To symbolize their commitment to facing life's obstacles together, they performed a symbolic "marriage" ritual by holding hands and swimming across a canal. During this crossing, Suzume lost her grip and the current swept her away; Kazuya immediately abandoned the goal of reaching the opposite bank to prioritize rescuing her, demonstrating his protective instincts and loyalty.

Following the start of his relationship with Suzume, Kazuya underwent significant personal development. He transformed from a troubled delinquent into the top academic student in his grade, excelling academically despite his previous reputation. These achievements secured his acceptance into a prestigious high school. In later appearances, his relationship with Suzume remains stable and caring. He consistently displays concern for her well-being, such as warning her to be careful to avoid falling, and rushing to her aid when she trips and sustains a bloody nose. This behavior highlights his matured protective nature and deep emotional investment in her safety and happiness.